Recent evidence suggests that injection drug use is increasing among suburban residents. Little research has focused on this trend, and the economic, social, and medical consequences have not been considered. To close this gap, we are proposing to identify, recruit, and study a valid sample of injectors who reside in Connecticut suburbs using respondent driven sampling (RDS). RDS was selected because of its strengths in identifying individuals from hidden populations and allowing statistical analysis of the sample. We are submitting this application in response to PAR-06-114, "Research on Pathways Linking Environments, Behaviors andHIV/AIDS". Not only will befocusing onanenvironment - thesuburbs - that has been neglected, but we will further focus on suburban injectors who inject in two distinct environments. Preliminary studies revealed that there are those who inject predominantly in the suburban town in which they reside and those who inject in urban areas where they obtain their drugs. We are building our study around the hypothesis that the two environments result in differences in (1) injection drug use patterns;(2) knowledge of, risk for, and prevalence of HIV, hepatitis B, and hepatitis C infections;(3) sociodemographic stability;and (4) the use of and barriers to services that reduce the negative consequences of injection. Our study will recruit a sample of 600 active injection drug users who reside in the suburbs. The sample will be studied through structured interviews, serology, and in-depth life histories. The sample will be followed longitudinally to ascertain whether the pattern of suburban or urban injection is stable and to identify factors associated with changes in injection environments and in risk for syringe-borne viral infection. Our study is designed able to answer questions including (1) how representative the sample is of the underlying population, (2) whether two groups of suburban injectors who differ based on where they inject differ in terms of disease knowledge, risk, and prevalences, (3) how much of the prevalence of HIV, HBV, and HCV can be predicted by individual, group, and environmental level variables, (4) how suburban injectors are geographically clustered and whether this affects disease prevalence, (5) how interaction with the criminal justice system influences drug use and risky injection practices, (6) which factors are associated with arrest and incarceration and (7) how injectors use drug treatment and disease prevention programs and what they perceive as the barriers to larger use of these services. To meet the objectives of this study, we have assembled an experienced, multidisciplinary team that can collect and analyze the quantitative, qualitative, and serological data and disseminate research findings to the scientific community through scholarly and public health channels and to the service community through our Center for Interdisciplinary Research on AIDS.